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Chemical Datasheet

HYDROCYANIC ACID, LIQUEFIED

6.1 - Poison Inhalation Hazard 3 - Flammable liquid
Chemical Identifiers | Hazards | Response Recommendations | Physical Properties | Regulatory Information | Alternate Chemical Names

Chemical Identifiers

The Chemical Identifier fields include common identification numbers, the NFPA diamond U.S. Department of Transportation hazard labels, and a general description of the chemical. The information in CAMEO Chemicals comes from a variety of data sources.
CAS Number UN/NA Number DOT Hazard Label USCG CHRIS Code
  • 74-90-8   (HYDROGEN CYANIDE)
  • Poison Inhalation Hazard
  • Flammable Liquid
NIOSH Pocket Guide International Chem Safety Card
Hydrogen cyanideexternal link
NFPA 704
Diamond Hazard Value Description
4
4 1
Blue Health 4 Can be lethal.
Red Flammability 4 Burns readily. Rapidly or completely vaporizes at atmospheric pressure and normal ambient temperature.
Yellow Instability 1 Normally stable but can become unstable at elevated temperatures and pressures.
White Special
(NFPA, 2010)
General Description
A clear colorless liquid with a faint odor of bitter almonds. Boiling point 78°F. Density 5.7 lb / gal. Flash point 0°F. Evaporates easily (or boils) at room temperature. Vapors slightly lighter than air. Deadly poison by all routes (absorption through skin of liquid, inhalation of vapors, etc). Prolonged exposure of closed containers to heat may cause violent rupture and rocketing.

Hazards

The Hazard fields include special hazard alerts air and water reactions, fire hazards, health hazards, a reactivity profile, and details about reactive groups assignments and potentially incompatible absorbents. The information in CAMEO Chemicals comes from a variety of data sources.
Reactivity Alerts
Air & Water Reactions
Highly flammable. Flame may easily travel back to source of leak. Vapors forms explosive mixtures with air. Soluble in water.
Fire Hazard
Unstabilized hydrocyanic acid may polymerize spontaneously with explosive violence. Flashback along vapor trail may occur. The explosion hazard is severe when this material is exposed to heat, flame, or oxidizers. It forms explosive mixtures with air, and will react with water, steam, acid, or acid fumes to produce highly toxic fumes of cyanides. It may decompose explosively upon contact with alkaline material. Avoid acetylaldehyde, alkaline materials, oxidizers, water, steam, acid, and acid fumes. Hydrocyanic acid solution is sensitive to light. It may become unstable and subject to explosion if stored for an extended time or exposed to high temperature and pressure. Avoid heat, flame or oxidizers. Hazardous polymerization may occur. Unstabilized hydrocyanic acid may polymerize spontaneously with explosive violence. Can polymerize at 122-140F or when catalyzed with traces of alkali. (EPA, 1998)
Health Hazard
It is super toxic. Breathing in a small amount of the gas or swallowing a very small amount may be fatal. Average fatal dose is 50-60 mg. A few minutes of exposure to 300 ppm may result in death. Exposure to 150 ppm for 1/2 to 1 hour may endanger life. (EPA, 1998)
Reactivity Profile
HYDROCYANIC ACID, [LIQUEFIED] reacts as an oxidizing agent and as a weak acid. Presents a severe explosion hazard when heated or exposed to oxidizing agents. Reacts violently with acetaldehyde. May polymerize explosively at elevated temperature (50-60°C). Polymerizes in the presence of traces of alkali [Wohler, L. et al., Chem. Ztg., 1926, 50, p. 761, 781]. May undergo rapid spontaneous polymerization leading to a fire Should be stabilized against this reaction by the addition of acid (such as phosphoric acid [Bond, J., Loss Prev. Bull., 1991, 101, p.3]. During the preparation of imidoester hydrochlorides, hydrogen chloride was rapidly passed over all alcoholic solution of hydrogen cyanide. An explosion ensued, even with cooling of the process [J. Org. Chem., 1955, 20, 1573].
Belongs to the Following Reactive Group(s)
Potentially Incompatible Absorbents

Use caution: Liquids with this reactive group classification have been known to react with the absorbents listed below. More info about absorbents, including situations to watch out for...

Response Recommendations

The Response Recommendation fields include isolation and evacuation distances, as well as recommendations for firefighting, non-fire response, protective clothing, and first aid. The information in CAMEO Chemicals comes from a variety of data sources.
Isolation and Evacuation
Excerpt from ERG Guide 117 [Gases - Toxic - Flammable (Extreme Hazard)]:

As an immediate precautionary measure, isolate spill or leak area for at least 100 meters (330 feet) in all directions.

SPILL: See ERG Table 1 - Initial Isolation and Protective Action Distances on the UN/NA 1051 datasheet.

FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions. (ERG, 2016)
Firefighting
Firefighting should be done from a safe distance. A few whiffs of gas, or liquid penetrating firefighter's protective clothing, could be fatal. Only special protective clothing should be worn. Water spray should be used to keep containers cool. Keep unnecessary people away; isolate hazard area and deny entry. Stay upwind; keep out of low areas. Ventilate closed spaces before entering them. Wear positive pressure breathing apparatus and special protective clothing. Evacuate area endangered by gas. Isolate for 1/2 mile in all directions if tank car or truck is involved in fire.

Use dry chemicals, alcohol foam, or carbon dioxide. Small fires: let burn unless leak can be stopped immediately. Large fires: water spray, fog or foam. Move container from fire area if you can do it without risk. Stay away from ends of tanks. Withdraw immediately in case of rising sound from venting safety device or any discoloration of tank due to fire. Cool container with water using unmanned device until well after fire is out. Isolate area until gas has dispersed. (EPA, 1998)
Non-Fire Response
Excerpt from ERG Guide 117 [Gases - Toxic - Flammable (Extreme Hazard)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames in immediate area). All equipment used when handling the product must be grounded. Fully encapsulating, vapor-protective clothing should be worn for spills and leaks with no fire. Do not touch or walk through spilled material. Stop leak if you can do it without risk. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Do not direct water at spill or source of leak. If possible, turn leaking containers so that gas escapes rather than liquid. Prevent entry into waterways, sewers, basements or confined areas. Isolate area until gas has dispersed. Consider igniting spill or leak to eliminate toxic gas concerns. (ERG, 2016)
Protective Clothing
Skin: Wear appropriate personal protective clothing to prevent skin contact.

Eyes: Wear appropriate eye protection to prevent eye contact.

Wash skin: The worker should immediately wash the skin when it becomes contaminated.

Remove: Work clothing that becomes wet should be immediately removed due to its flammability hazard(i.e. for liquids with flash point < 100°F)

Change: No recommendation is made specifying the need for the worker to change clothing after the work shift.

Provide: Eyewash fountains should be provided in areas where there is any possibility that workers could be exposed to the substance; this is irrespective of the recommendation involving the wearing of eye protection. Facilities for quickly drenching the body should be provided within the immediate work area for emergency use where there is a possibility of exposure. [Note: It is intended that these facilities provide a sufficient quantity or flow of water to quickly remove the substance from any body areas likely to be exposed. The actual determination of what constitutes an adequate quick drench facility depends on the specific circumstances. In certain instances, a deluge shower should be readily available, whereas in others, the availability of water from a sink or hose could be considered adequate.] (NIOSH, 2016)
DuPont Tychem® Suit Fabrics
Tychem® Fabric Legend
QS = Tychem 2000 SFR
QC = Tychem 2000
SL = Tychem 4000
C3 = Tychem 5000
TF = Tychem 6000
TP = Tychem 6000 FR
BR = Tychem 9000
RC = Tychem RESPONDER® CSM
TK = Tychem 10000
RF = Tychem 10000 FR
Testing Details
The fabric permeation data was generated for DuPont by independent testing laboratories using ASTM F739, EN369, EN 374-3, EN ISO 6529 (method A and B) or ASTM D6978 test methods. Normalized breakthrough times (the time at which the permeation rate is equal to 0.1 µg/cm2/min) reported in minutes. All liquid chemicals have been tested between approximately 20°C and 27°C unless otherwise stated. A different temperature may have significant influence on the breakthrough time; permeation rates typically increase with temperature. All chemicals have been tested at a concentration of greater than 95% unless otherwise stated. Unless otherwise stated, permeation was measured for single chemicals. The permeation characteristics of mixtures can deviate considerably from the permeation behavior of the individual chemicals. Chemical warfare agents (Lewisite, Sarin, Soman, Sulfur Mustard, Tabun and VX Nerve Agent) have been tested at 22°C and 50% relative humidity per military standard MIL-STD-282.
Normalized Breakthrough Times (in Minutes)
Chemical CAS Number State QS QC SL C3 TF TP BR RC TK RF
HCN (Hydrogen cyanide) (>95%, gas) 74-90-8 Vapor 30 >480 >480 >480 >480 >480
HCN (Hydrogen cyanide) (>95%, liquid, 21° C) 74-90-8 Liquid 105 105 >480 105
Hydrocyanic acid (>95%, gas) 74-90-8 Vapor 30 >480 >480 >480 >480 >480
Hydrocyanic acid (>95%, liquid, 21° C) 74-90-8 Liquid 105 105 >480 105
Hydrogen cyanide (>95%, gas) 74-90-8 Vapor 30 >480 >480 >480 >480 >480
Hydrogen cyanide (>95%, liquid, 21° C) 74-90-8 Liquid 105 105 >480 105
> indicates greater than.
A blank cell indicates the fabric has not been tested. The fabric may or may not offer barrier.

Special Warnings from DuPont

  1. Serged and bound seams are degraded by some hazardous liquid chemicals, such as strong acids, and should not be worn when these chemicals are present.
  2. CAUTION: This information is based upon technical data that DuPont believes to be reliable. It is subject to revision as additional knowledge and experience are gained. DuPont makes no guarantee of results and assumes no obligation or liability...
    ... in connection with this information. It is the user's responsibility to determine the level of toxicity and the proper personal protective equipment needed. The information set forth herein reflects laboratory performance of fabrics, not complete garments, under controlled conditions. It is intended for informational use by persons having technical skill for evaluation under their specific end-use conditions, at their own discretion and risk. Anyone intending to use this information should first verify that the garment selected is suitable for the intended use. In many cases, seams and closures have shorter breakthrough times and higher permeation rates than the fabric. Please contact DuPont for specific data. If fabric becomes torn, abraded or punctured, or if seams or closures fail, or if attached gloves, visors, etc. are damaged, end user should discontinue use of garment to avoid potential exposure to chemical. Since conditions of use are outside our control, we make no warranties, express or implied, including, without limitation, no warranties of merchantability or fitness for a particular use and assume no liability in connection with any use of this information. This information is not intended as a license to operate under or a recommendation to infringe any patent or technical information of DuPont or others covering any material or its use.

(DuPont, 2018)

First Aid
Warning: Hydrocyanic acid may be fatal if inhaled, swallowed, or absorbed through skin or mucous membranes. Caution is advised.

Signs and Symptoms of Acute Hydrocyanic Acid Exposure: Signs and symptoms of acute exposure to hydrocyanic acid may include hypertension (high blood pressure) and tachycardia (rapid heart rate), followed by hypotension (low blood pressure) and bradycardia (slow heart rate). Cherry red mucous membranes and blood may be noted. Cardiac arrhythmias and other cardiac abnormalities are common. Cyanosis (blue tint to the skin and mucous membranes) may be observed. Weakness, headache, vertigo (dizziness), agitation, giddiness, salivation, nausea, and vomiting, may be followed by combative behavior, convulsions, paralysis, protruding eyeballs, dilated and unreactive pupils, and coma. Tachypnea (rapid, shallow respirations) or hyperpnea (rapid, deep respirations) may be followed by respiratory depression. Lung hemorrhage and pulmonary edema may also occur. Hydrocyanic acid is may be irritating to the skin, eyes, and mucous membranes. Lacrimation (tearing) and a burning sensation of the mouth and throat are common.

Emergency Life-Support Procedures: Acute exposure to hydrocyanic acid may require decontamination and life support for the victims. All exposed persons should be transported to a health care facility as quickly as possible. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.

Inhalation Exposure:
1. Move victims to fresh air. Emergency personnel should avoid self-exposure to hydrocyanic acid.
2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. IMMEDIATELY begin administering 100% oxygen to all victims. Monitor victims for respiratory distress.Warning: To prevent self-poisoning, avoid mouth-to-mouth breathing; use a forced-oxygen mask. Direct oral contact with hydrocyanic acid- contaminated persons or their gastric contents can result in self- poisoning.
3. RUSH to a health care facility!
4. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

Dermal/Eye Exposure:
1. Remove victims from exposure. Emergency personnel should avoid self- exposure to hydrocyanic acid.
2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. IMMEDIATELY begin administering 100% oxygen to all victims. Monitor victims for respiratory distress.Warning: To prevent self-poisoning, avoid mouth-to-mouth breathing; use a forced-oxygen mask. Direct oral contact with hydrocyanic acid- contaminated persons or their gastric contents can result in self- poisoning.
3. RUSH to a health care facility!
4. Remove contaminated clothing as soon as possible.
5. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.
6. Wash exposed skin areas twice with soap and water.
7. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

Ingestion Exposure:
1. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. IMMEDIATELY begin administering 100% oxygen to all victims. Monitor victims for respiratory distress.Warning: To prevent self-poisoning, avoid mouth-to-mouth breathing; use a forced-oxygen mask. Direct oral contact with hydrocyanic acid- contaminated persons or their gastric contents can result in self- poisoning.
2. RUSH to a health care facility!
3. DO NOT induce vomiting or attempt to neutralize!
4. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
5. Activated charcoal may be administered if victims are conscious and alert. Use 15 to 30 g (1/2 to 1 oz) for children, 50 to 100 g (1-3/4 to 3-1/2 oz) for adults, with 125 to 250 mL (1/2 to 1 cup) of water.
6. Promote excretion by administering a saline cathartic or sorbitol to conscious and alert victims. Children require 15 to 30 g (1/2 to 1 oz) of cathartic; 50 to 100 g (1-3/4 to 3-1/2 oz) is recommended for adults. (EPA, 1998)

Physical Properties

The Physical Property fields include properties such as vapor pressure and boiling point, as well as explosive limits and toxic exposure thresholds The information in CAMEO Chemicals comes from a variety of data sources.
Chemical Formula:
  • HCN
Flash Point: 0 ° F (EPA, 1998)
Lower Explosive Limit (LEL): 5.6 % (EPA, 1998)
Upper Explosive Limit (UEL): 40 % (EPA, 1998)
Autoignition Temperature: 1004 ° F (USCG, 1999)
Melting Point: 7.9 ° F (EPA, 1998)
Vapor Pressure: 630 mm Hg (EPA, 1998)
Vapor Density (Relative to Air): 0.901 (EPA, 1998)
Specific Gravity: 0.699 (EPA, 1998)
Boiling Point: 78.1 ° F at 760 mm Hg (EPA, 1998)
Molecular Weight: 27.03 (EPA, 1998)
Water Solubility: Miscible (NIOSH, 2016)
Ionization Potential: 13.60 eV (NIOSH, 2016)
IDLH: 50 ppm (NIOSH, 2016)

AEGLs (Acute Exposure Guideline Levels)

Final AEGLs for Hydrogen cyanide (74-90-8)
Exposure Period AEGL-1 AEGL-2 AEGL-3
10 minutes 2.5 ppm 17 ppm 27 ppm
30 minutes 2.5 ppm 10 ppm 21 ppm
60 minutes 2 ppm 7.1 ppm 15 ppm
4 hours 1.3 ppm 3.5 ppm 8.6 ppm
8 hours 1 ppm 2.5 ppm 6.6 ppm
(NAC/NRC, 2017)

ERPGs (Emergency Response Planning Guidelines)

Chemical ERPG-1 ERPG-2 ERPG-3
Hydrogen Cyanide (74-90-8) NA 10 ppm 25 ppm
NA = not appropriate.
(AIHA, 2016)

PACs (Protective Action Criteria)

Chemical PAC-1 PAC-2 PAC-3
Hydrogen cyanide; (Hydrocyanic acid) (74-90-8) 2 ppm 7.1 ppm 15 ppm LEL = 56000 ppm
(DOE, 2016)

Regulatory Information

The Regulatory Information fields include information from the U.S. Environmental Protection Agency's Title III Consolidated List of Lists, the U.S. Department of Homeland Security's Chemical Facility Anti-Terrorism Standards, and the U.S. Occupational Safety and Health Administration's Process Safety Management of Highly Hazardous Chemicals Standard List (see more about these data sources).

EPA Consolidated List of Lists

Regulatory Name CAS Number/
313 Category Code
EPCRA 302
EHS TPQ
EPCRA 304
EHS RQ
CERCLA RQ EPCRA 313
TRI
RCRA
Code
CAA 112(r)
RMP TQ
Cyanide Compounds N106 & 313
Hydrocyanic acid 74-90-8 100 pounds 10 pounds 10 pounds X P063 2500 pounds
Hydrogen cyanide 74-90-8 100 pounds 10 pounds 10 pounds 313 P063 2500 pounds

(EPA List of Lists, 2015)

DHS Chemical Facility Anti-Terrorism Standards (CFATS)

RELEASE THEFT SABOTAGE
Chemical of Interest CAS Number Min Conc STQ Security
Issue
Min Conc STQ Security
Issue
Min Conc STQ Security
Issue
Hydrocyanic acid 74-90-8 1.00 % 2500 pounds toxic
Hydrogen cyanide; [Hydrocyanic acid] 74-90-8 4.67 % 15 pounds WME

(DHS, 2007)

OSHA Process Safety Management (PSM) Standard List

Chemical Name CAS Number Threshold Quantity (TQ)
Hydrogen Cyanide, Anhydrous 74-90-8 1000 pounds

(OSHA, 2011)

Alternate Chemical Names

This section provides a listing of alternate names for this chemical, including trade names and synonyms.